Removable storage media with improved data integrity

Abstract

A technique for storing or backing up data to a removable media such as a CD or DVD with an enhanced probability that such data can be successfully read or recovered from such media subsequent to the writing / storing / backing-up of the data. This enhanced probability is achieved by storing the data to be copied to the media in multiple different physical locations of the media, such that a plurality of duplicate copies of the data exists on the media. Because there are multiple copies of the data stored on the media, the probability of being able to successfully read at least one good copy of the data is enhanced. For example, if one of the copies cannot be successfully read due to an unrecoverable error, another of the copies can be used to satisfy the read or restore operation. It is also possible to read all copies of the data in response to a read / restore operation, and any differences in the read data will indicate an error with at least one of the copies. Selection of which copy to select and use to satisfy the read request is based on a vote, where the copies are matched against one another, and the copy having the most matches with other copies is deemed to be the good copy and is used to satisfy the read or restore operation.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates generally to techniques for saving and restoring data, and more particularly the present invention relates to a computer implemented method, system and computer usable program code for improving integrity of data stored on removable storage media such as compact discs and digital versatile / video discs.[0003]2. Description of the Related Art[0004]As data storage densities continue to increase, greater and greater amounts of data can be stored in smaller and smaller containers. For example, today's single-sided, single-layer digital versatile / video disc (DVD) can hold 4.7 gigabytes (GB) of data. In the near future, a single-sided, single-layer HD DVD will hold 15 GB of data, and a comparable Blu-ray Disc will hold 25 GB of data. While not having the same capacity as DVDs, compact discs (CDs) are also useful for saving data due to their relatively low costs.[0005]Use of removable storage media...

AI Technical Summary

Benefits of technology

This approach enhances the probability of successfully reading or recovering data by ensuring at least one good copy is available, even if one copy is defective, thereby improving data integrity and reliability.

Problems solved by technology

However, with such increased use comes associated risk.

Because these media contain so much data, media defects or a natural aging process can result in the loss of significant amounts of data.

Such data loss comes from things such as physical damage of the media (breaking, melting, scratching) by careless or improper handling or use of the media, or blocking of the laser light used to access the media (by dirt, paint, ink, glue, or corrosion of the reflecting layer).

Certain defects may even exist on raw, never-written or never-used media due to manufacturing defects.

However, such ECC coding can only handle so much damage before an unrecoverable error occurs.

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